99% of drives are just... slow... at ripping dual-layer movies.
The ones that go through very fast are single layer movies. Those not only need very little compression, but they rip at probably close to the full rated speed of the drive (which I'm assuming is 16x read).
Dual-layer movies, on the other hand, usually START at 4x and ramp up to 9-10x TOPS, usually more like 7-8x depending on the price of tea in China and the phase of Jupiter in the house of Saturn.
Nothing to be done, man.